Every time I go into a store I keep an eye out for cheap stuff that's hackable.   I've been seeing in CVS pharmacy and a few other places the "Thunder Tumbler" or similarly named R/C car.  CVS has had in the past good hackable toys so I thought to take a chance and see what you got for $9.99 plus tax.  Turns out, you get a sweet little robot platform that has some things going for it.

* Dual motors and skid steering.  Motors, gearboxes and wheels are already assembled and mounted on a chassis.  Not the best of chassis but still it's workable.  The motors where designed to run at 6V at full speed, but we don't need nearly the top speed this toy was meant to do so four rechargeable AA batteries (4.8V) should work fine.

* The printed circuit board that drives the toy itself is a basic single sided board with though-hole components, not surface mount.    This is the key thing that makes this toy a sweet hackable deal.      It has a transistor based H-bridge with forward and reverse for each motor.  You can hack into the PCB with a little desoldering and presto, that dual channel h-bridge is now doing your bidding.   

* The data signals for the h-bridge can be plain old 5v, straight out of your microcontroller.  It will probably work with 3.3V signals as well, I just haven't tried it.

* As mentioned the chassis is OK but not great.  Still, it allows me to mount my normal setup for this sort of thing, a solderless breadboard with an arduino clone attached.  (The DC boarduino from adafruit industries).  

* The built-in battery case takes (4) AA's.   Four rechargeable ones works out great as the motor power supply.
* They even give you a 9V battery which I use to power the microcontroller via the boarduino's voltage regulator.    Having separate batteries for the motors (the rechargable AA's) and for the data/control electronics (microcontrollers, sensors, etc) is a good idea to cut down on interference problems.

Step 1: Tools and Materials

To start you'll need a Thunder Tumbler R/C Car, available from many stores.

Along with that, you need a power source for the motors.  I would suggest four AA batteries (rechargeable or not) that go into the regular battery slot on the car.

The point of this whole thing is to turn this toy into something that can be controlled easily with a microcontroller, so you should have your own microcontroller and know how to program it.  The basic hack is controller neutral but does have some requirements:

* To control both left and right motors in forward and reverse, you need 4 digital outputs from the controller, preferably PWM outputs for all 4 so you can control the speed of the motors.  That's for the simple, basic hack.   The arduino has 6 PWM outputs, so I was covered there.   A more advanced hack can get that down to 2 PWM outputs and 2 regular digital outputs needed for controllers with less PWM ability.  However after playing around with it I found the effort needed to do so was not worth it.    YMMV.   I will describe the more advanced hack and what it will take to accomplish.

* I tested it with a 5V controller, so 5V data signals to the h-bridges.  This worked well.  They probably would work with 3.3V signals, but that has not been tested.

* I desoldered the standard DIP package 16 pin chip on the PCB and replaced it with a 16 pin IC socket.  You can do that or put in headers of some flavor if you so wish.    Really it's about what will work for you, just have something that allows you to connect into your controller as needed.  

Tool wise, you'll need things like a #1 phillips screwdriver, an xacto knife or other cutting tool, a soldering iron and desoldering ability of some sort.   I never could get the sucking up desoldering tools to work well so use the copper mesh stuff instead.  Again, YMMV.

<p>A BIG THANK YOU. I used a Thunder Tumbler to drive 2 wheels on a 1:6 scale GI Joe/Action Man BSA and sidecar. My problem now is it that it all moves too fast. Can I replace the 4 x AA batteries with just 2 or 3 AAs if I replace the original cartridge type battery holder with a standard AA battery holder and solder up a PP3 battery connector clip to the terminal points on the board?</p>
<p>Woah, thanks for making this, I have one of these lying around that I got out the other day hoping to figure out a nice way to hack it into something better, and here it is. Thanks!</p>
Just got one without the remote control for $3. I know someone who has a remote control to test it. looks like loads of fun.
I bought a tumbler! I followed your instructable and I sucsessfully built a robot! Thank you soooo much. I joined a computer club at school. They play with microcontrollers and stuff. Now I have a head start.
<p>I am facing the same problem as rikos7. I have tried the voltage. The problem is the two pins respond in both directions as in the wheel spinning forward or backward.</p> <p>&nbsp;</p> <p>PLEASE REPLY SOON!</p>
I am buying a tumbler
Wow! Is the internet great, or what? I got one of these cars at a thrift store for $2 without the controller. I disassembled it and poked +V around the board to find the inputs to the H-bridge, de-soldered the receiver (a daughter board in mine) and removed all the blinky lights. I put pwm in from my Arduino to test for speed control and it worked great. THEN I find your instructable! Your right, these are a goldmine of robot parts...<br />
I couldnt find the tumbler car, so got another rc robot thing i was going to try. However, how do i go about figuring out the pins on the microcontroller. Is there a voltage i need to try to measure when I push the rc controller units sticks, just trace the circuit board or something else? The the pcb in the rc car looks alot like yours, other than the board seems a little less cheap.
Would be interesting to see if the controller could be placed on the wireless remote to transmit programmed commands to the car.<br /> <br /> <br />
your &nbsp;project is very good and i followed it to the teeth&nbsp; my&nbsp; car worked but because it only has one motor&nbsp; to drive and the other to turn the front renewals&nbsp; 360 dig&nbsp; i need a script to control&nbsp; the turn .i am not&nbsp; so good&nbsp; writing script so if&nbsp; anyone could&nbsp; help&nbsp;&nbsp; i need one motor to run 10 sec&nbsp; stop then the other to run for&nbsp; a very short instant&nbsp;&nbsp;&nbsp;very short stop&nbsp; in a&nbsp; lupe
<style type="text/css"><![CDATA[p.MsoNormal, li.MsoNormal, div.MsoNormal { margin-top: 0.0in; margin-right: 0.0in; margin-bottom: 10.0pt; margin-left: 0.0in; line-height: 115.0%; font-size: 11.0pt; font-family: Calibri , sans-serif; } *.MsoChpDefault { } *.MsoPapDefault { margin-bottom: 10.0pt; line-height: 115.0%; } div.Section1 { page: Section1; } ]]></style> <p class="MsoNormal">I went through two years of electronics with a few harbor freight <span style="">&nbsp;</span>DMM. Even one of my teachers went out and got some&hellip; showed the class that is all you need. <span style="">&nbsp;</span>Great job on the instructable, I&rsquo;m going to have to stop by and pick one up.</p>
YES&nbsp; YES&nbsp; YES&nbsp; very&nbsp; nice hi i am a new&nbsp; comer and i have an older modle of the tumbler looks the same&nbsp; but the frunt wheels rotate&nbsp; 360 dg&nbsp; the curcit board in the same.question if ihave a arduino moter sheld can i&nbsp; elemenate the curcit doard and use the moter shild&nbsp; to controle the movements of the car
I don't have a motor shield so I don't know exactly.&nbsp; One of the reasons to use this guy is because it already has built in the motor controller h-bridges that you know work, so you don't have to use the ones on the motor shield.<br /> <br /> Having said that, you can bypass the Tumbler PCB and use the motor shield.&nbsp;&nbsp; Be careful to cut/desoder the wires of the motors off the PCB and attach them to the screw terminals on the shield.&nbsp; The current draw on these motors is around the max that the L293D chip on the shield can take, so you'll have to experiment to see if they do play well with each other.&nbsp; <br /> <br />
Cool!&nbsp; Very detailed Instructable. &nbsp;:)<br />

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Bio: Named "Emblematic of the Instructables Universe" by the New York Times, I'm a maker and designer who enjoys looking at things sideways and playing ... More »
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